The present invention relates to systems and methods for designing components, subsystems, systems and structure of aircraft, and more particularly to a system and method for predicting and analyzing the needed electrical power generation and distribution system (EPGDS) components, subsystems and systems and the performance of such an EPGDS, for an aircraft in any phase of the design of the aircraft.
A CDROM with two files including materials forming a portion of a computer program for the present invention is included on a CDROM accompanying the present application. These two files are hereby incorporated by reference into the present application. The first file is xe2x80x9cFunctional Spec. doc (created May 4, 2001, 2,083,372 bytes) and the second file is xe2x80x9cEpgds.doc+xe2x80x9d (created May 7, 2001, 19,968 bytes)
A recurring challenge faced by aircraft weight engineers is to provide good weight information early in an aircraft aircraft design process. This is necessary in order to be able to influence the aircraft design at relatively low cost and when the opportunity to do so exists.
Present day parametric/statistical weight analysis methods are grossly inadequate in ensuring weight efficiency and weight compliance of aerospace products. These methods produce estimates with large, unexplainable tolerances and are insensitive to key design parameters, thus precluding the ability to adequately discriminate between design variations or perform rapid trade studies. This makes early, effective weight control and design guidance difficult and increases the cycle time for design convergence. Consequently, weight growth of an aircraft under design occurs during the detailed design phase, thus often requiring costly rework and weight reduction programs. This also results in heavier than necessary aircraft empty weights, thus negatively effecting the competitiveness of the products.
In the preliminary or conceptual design phase of an aircraft, many factors are considered involving alternative electrical subsystems which each have many pluses and minuses. Some important trade factors such as reliability, maintainability and/or dependability cost have historically been done by disciplines other than mass properties. Quick assessments of this suite of trade factors, in addition to the mass properties of various electrical components and subsystems, can be extremely useful during the definition phase of the aircraft design process in minimizing the overall weight of the aircraft.
It would therefore be desirable to provide a design approximation system and method which provides sufficient design detail during the definition phase of an aircraft design to calculate not only the mass properties of various component level parts of an aircraft""s EPGDS, but also system attributes such as cost, reliability and maintainability through calculations using knowledge-based design principles. It would also be highly desirable to present such information in a format that allows an aircraft designer to easily perform multi-level trade studies to gauge the costs and benefits of alternative designs of subsystems and/or component level items of EPGDS designs.
It would also be desirable to provide such a design approximation tool as described above which is capable of being used with a minimum of as few as two aircraft parameters being input by the aircraft designer or engineer, such as the number of engines and the maximum take off weight (MTOW) of an aircraft.
It would be further desirable to provide such a knowledge-based, design approximation and weight assessment tool which provides early rapid definitive weight determination and control at any stage in a product definition cycle, and which can facilitate early and rapid dependability cost determination and control, as well as provide information on other system attributes such as reliability and maintainability.
The above and other objectives are provided by a system and method which provides design-based weight analysis of an electrical power generation and distribution system for an aircraft from inputs involving a combination of aircraft level configuration data, as well as from knowledge based algorithms. The system and method of the present invention uses automated knowledge-based algorithms to provide the initial characterization of the EPGDS for the aircraft.
The method and apparatus of the present invention provides for evaluating the electrical power generation and distribution system (EPGDS) of an aircraft from a plurality of perspectives involving weight, body station center of gravity, dependability cost, reliability and maintainability. The invention calculates multiple system attributes of the EPGDS which allows rapid trade study capability in comparison with alternative EPGDS designs. The invention significantly reduces cycle time in the risk assessment process and allows an aircraft designer to more easily control or influence the overall weight of the aircraft.
In one preferred form, the present invention is provided in the form of a user friendly, robust software program. Calculated values for all aircraft and EPGDS parameters are constructed from a minimum of two inputs: the number of engines (NE) to be used on an aircraft and the maximum takeoff weight (MTOW) of the aircraft. Three additional high level parameters/variables that the design engineer can modify are aircraft type, the number of passengers to be accommodated, and the range of the aircraft.
From the above high level parameters input by the designer, the system and method calculates a wide range of information concerning the EPGDS which is presented to the user in a plurality of easily accessible and viewable screens formats in several distinct categories. An Electronic Data Dictionary provides the user with access to the various formulas and other information used by the software in making these calculations and estimates.
The information calculated by the software relates to a plurality of distinct design considerations. These design considerations are categorized as xe2x80x9cconfigurationxe2x80x9d, xe2x80x9celectrical loadsxe2x80x9d, xe2x80x9carchitecturexe2x80x9d, xe2x80x9cgenerationxe2x80x9d, xe2x80x9cdistributionxe2x80x9d, xe2x80x9csystem attributesxe2x80x9d and xe2x80x9cweight summariesxe2x80x9d. The xe2x80x9cconfigurationxe2x80x9d information includes information pertaining to specific dimensions of components of the aircraft as well as body station location information for various major structural components of the aircraft. It also contains relevant flight control, frequency type, and technology era information. The xe2x80x9celectrical loadsxe2x80x9d information pertains to the AC and DC electrical loads that are expected to be experienced by the aircraft during six flight phases of aircraft operation, as well as the number and types of various pumps, fans, motors, transformers and other electrical components, and the power requirements of such components. The xe2x80x9carchitecturexe2x80x9d information provides the designer with information on the architectures of the major subsystems of the aircraft. The xe2x80x9cgenerationxe2x80x9d information provided to the designer is directed to various electrical generation components and their electrical load requirements. The xe2x80x9cdistributionxe2x80x9d information is directed to various power feeder and power panel subsystems and analysis of variables relating to their components. The xe2x80x9csystems attributesxe2x80x9d information provides the designer with dependability cost, reliability and maintainability information. Each one of these three system attribute submodules further provides a variety of specific information relating to the dependability cost, reliability and maintainability of numerous line replaceable units (LRUs) of the aircraft and the costs and safety probabilities associated with maintaining such component parts and designs.
The Electronic Data Dictionary contains all engineering theory and formulas related to the calculations performed by the method and apparatus of the present invention. The electronic data dictionary allows the designer to review the theoretical equations and associated text explanations associated with each parameter/variable operated on by the software through a xe2x80x9cHelpxe2x80x9d menu function which is displayed on all of the screens of the software program. A xe2x80x9cNotesxe2x80x9d field is used to provide a simplified explanation of the formula being viewed. A separate functional specification attached as Appendix A, and hereby incorporated by reference, describes the sequence of calculation of the xe2x80x9cvarnamesxe2x80x9d in the data dictionary and screen layouts.
The formulas and algorithms used by the method and apparatus of the present invention are applicable to all design phases. This permits seamless use through design phases from preliminary through detailed design, thus avoiding discontinuities caused by switching between various estimation methods. If better knowledge of any one of the numerous plurality of parameters/variables exists, it is possible to override previously input values calculated by the method and to xe2x80x9clock inxe2x80x9d those new values for subsequent calculations performed by the invention. Calculations then proceed by the software in a xe2x80x9ctumble-downxe2x80x9d manner, thus affecting the determination of xe2x80x9cdownstreamxe2x80x9d calculations. Having the designer insert known, more accurate values and re-calculate downstream parameters improves the accuracy of downstream parameters/variables. Once a parameter value is locked in by the user, it cannot be changed by the invention by higher-level xe2x80x9cupstreamxe2x80x9d values. Thus, xe2x80x9clocking inxe2x80x9d better values allows the designer to incrementally improve the accuracy of the information generated by the software as the aircraft design process progresses through the preliminary phase to the detailed design phase.
The method and apparatus of the present invention also makes it possible to do trade studies comparing competing EPGDS candidates from the several perspectives of the system attributes. The software of the present invention is very fast when compared to conventional, manual techniques. Selection of specific part and LRU level components can be changed by the user at various locations within the software. The present invention also supports design activities associated with upgrading derivative aircraft as well as the design of new aircraft.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.